Method of molding clay articles.



M. E. GATES.

METHOD 0F MOLDING CLAY ARTICLES.

APPLICATION man FEB. 1, 1913.

1,177,240, Patented Mar. 28, 1916.

MAJOR E. GATES, OF TERRA GOTTA, ILLINOIS.

METHOD OF MOLZDING CLAY ARTICLES.

Specification of Letters Patent.

Application led February 7, 1913. Serial No', 746,773.

To all lwhom, it may concern.' Y

Be it known that I, MAJOR E. Gams, a citizen of the United States,resldlng at Terra Cotta, in the county of McHenry and State of Illinois,have invented a new and useful Improvement in Methods of Molding ClayArticles, of which the following is a specification.

My invention relates to an improvement in the art of molding articles ofclay, which vI have more immediately devised for terracotta work, andtherefore confine thereto the description hereinafter contained.

The ordinary practice in molding such articles as terra-cotta tiles isto introduce the prepared clay in plastic condition, and which isusually provided in sheet or block form of about one and one-quarterinches in thickness, into the mold to be pressed therein to conform toits contour, after which cross-ribs of the same material are inserted,whereupon the molded article is freed from the mold, by .taking thelatter apart, to be subsequently transferred to a kiln and burned. Theoperator performs the work by pressing the clay7 with his hands to shapeit in the mold. This is necessarily an arduous operation, slow andtherefore expensive, and even with great care often results inimperfections in the article by failure to press the clay to the contourof the mold uniformly throughout the latter, and these imperfectionsrequire handling of the molded article to correct them, whereby theexpense of manufacture is still further increased.

The object of my invention is to greatly expedite the molding operationand render the molded product more uniformly perfect, thereby verymaterially reducing the cost. This I accomplish by performing themolding with air-pressure. However, the mold used for work of the kindunder consideration is a weak structure, comprising a base and separableside-walls thereon and is required to be formed of a material that willreadily separate from thev surfaces of the molded article, and plasterof Paris is therefore used for the mold, the sides of which areseparably held together by a light metal band removably surroundingthem. This mold-structure is altogether too weak, however, to withstandinternal airpressure sufficiently high (say sixty pounds to the squareinch) to mold the clay, and it should, moreover, at least for greatereffectiveness, be applied against a suitable flexible medium interposedbetween it and the clay in4 the mold. To counteract the weakness of themold, referred to, I introduce the molding air-pressure underconfinement not only upon the clay placed in thev mold, but also aboutthe mold-structure, thereby sustaining the latter against d1sruption;and as the interposed medium, referred to, I employ a bag preferably ofelastlc rubber, all as hereinafter described and illustrated in the ing,in which- Figure 1 is a view in the.`"crosssectional elevatwn of a moldequipped with means suitable for the practice of my improvement andshowing the clay laid into it preparatory to subjection thereof to myimproved molding operation, and Fig. 2 is a simllar view of the entireapparatus, showing the molding operation completed therein.

The mold consists of a base 3, and sides 4secured thereon in anysuitable way to render them removable with desirable facility, the partsbeing composed of plaster of Paris and forming the mold-chamber 5. Acover 7, preferably of cast metal, envelops the mold, being spaced aboutit and clamped at 1ts base-flange 6 to a suitable bed or table 8; andair-pressure is admissible from any suitable source (not shown) into thespace about the mold through a nipple 9 on the cover. A flexible mediuml0, impervious to air, preferably sheet-rubber in the form of a baglining the cover 7, extends loosely in the cover, whereby, when thelatter is adjusted over the mold, the sheet covers it as an apron, asshown in Fig. l.

To operate in accordance with my invention, pieces 11 of the preparedlterra-cotta clay are laid in the mold-chamber 5 to roughly conform themto the surfaces thereof, whereupon the bag-carrying cover 7 is appliedover the mold and fastened in place,

accompanying draw- Patented lum. es, raie.

and the air-pressure (of about sixty pounds,

forced out of the mold through its joints and pores. Upon completion ofthe molding operation, the'cover and bag are removed, and the mold istaken apartto release the molded article 12 (Fig. 2) fortransfer to thekiln. The entire operation consumes a few seconds as against a fewminutes in the case of small articles 12y and many minutes' in the caseof largearticles molded in the ordinary way, With the advantage ofsaving in time and labor and that of performing the Work.more perfectly.In fact, it is material against the fragile walls is bal-h rial in amold having fragile walls about,-

a mold-chamber approximating in depth the height of the walls whichconsists in subjecting the 'plastic material within the moldchamber andalso the outer surface of the Walls simultaneously to fluid-pressure,whereby the outward pressure of the plastic anced by the exteriorfluid-pressure.

2. The method of molding plastic material in a mold having fragile wallsabout a mold-chamber approximating in depth the height of the Wallswhich consists in covering the mold and thereby forming a space about itwithin the cover, exibly'enveloping in said space the mold-chamber andforcing air under pressure into said space against the envelop tosimultaneously press it against thepexterior of the .fragile walls andthe material in the mold-chamber, for the purpose set forth. v

3. The method of molding plastic material in a mold havin fragile wallsabout a mold-chamber, whic consists in covering the mold and therebyforming a space about it within the cover, enveloping in said space themold-chamber with a flexible bag, and forcing air under pressure intothe bag to expand it simultaneously against the exterior of the fra ileWalls and the material in the mold-cham er, for the purpose set forth.

4. The method of molding articles out of plastic clay in a mold havingfragile walls about a mold-chamber, which consists in laying the plasticclay in pieces in the moldchamber, applying over the mold a cover and arubber bag therein to envelop the mold-chamber, and forcing air .underpres? sure into the bag to expand it simultaneously against the exteriorof the fragile walls and the plastic clay in Athe moldchamber, for thepurpose set forth.

MAJOR E. GATES.

In presence lof y A. C. FISCHER, O. C. AvIsUs.

